package com.boot2.core.utils;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @author zhangweilin
 * @date 2018/10/4 21:39
 * @description: 订单号生成工具，生成非重复订单号，理论上限1毫秒1000个，可扩展
 */
public class OrderNumUtil {
    /**
     * 每毫秒生成订单号数量最大值
     */
    private static final int maxPerMSECSize = 1000;
    /**
     * 锁对象，可以为任意对象
     */
    private static Object lockObj = "lockerOrder";
    /**
     * 订单号生成计数器
     */
    private static long orderNumCount = 0L;

    public static String genOrderNum(String prefix, int len) {
        // 最终生成的订单号
        String orderNum = "";
        synchronized (lockObj) {
            // 取系统当前时间作为订单号变量前半部分，精确到毫秒
            long nowLong = Long.parseLong(new SimpleDateFormat("yyyyMMddHHmmssSSS").format(new Date()));
            // 计数器到最大值归零，可扩展更大，目前1毫秒处理峰值1000个，1秒100万
            if (orderNumCount >= maxPerMSECSize) {
                orderNumCount = 0L;
            }
            //组装订单号               
            String countStr = maxPerMSECSize + orderNumCount + "";
            orderNum = prefix + nowLong + RandomUtils.randomNumbers(len) + countStr.substring(1);
            orderNumCount++;
            return orderNum;
        }
    }

    /**
     * 生成非重复订单号，理论上限1毫秒1000个，可扩展
     */
    public static String genOrderNum(String prefix) {
        return genOrderNum(prefix, 5);
    }

    public static void main(String[] args) {
        // 测试多线程调用订单号生成工具
        try {
            for (int i = 0; i < 200; i++) {
                Thread t1 = new Thread(new Runnable() {
                    @Override
                    public void run() {
                        String orderNum = OrderNumUtil.genOrderNum("H");
                        System.out.println("orderNum = " + orderNum);
                    }
                }, "at" + i);
                t1.start();
                Thread t2 = new Thread(new Runnable() {
                    @Override
                    public void run() {
                        String orderNum = OrderNumUtil.genOrderNum("F");
                        System.out.println("orderNum = " + orderNum);
                    }
                }, "bt" + i);
                t2.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
